The objectives of this project are to describe and evaluate the determinants of gastric dysplasia and chronic atrophic gastritis, conditions thought to be precursors to stomach cancer, in a population in Shandong, China where stomach cancer rates are high. This will be accomplished by a population-based endoscopic survey of 3,000 adults age 35-64 to classify gastric status, with information on diet, tobacco consumption, medical history and other exposures obtained via interviews and measurements of nutrients and other substances in blood, urine, and gastric juice. Rates of transitions of these gastric lesions to cancer will be determined via follow-up of the study population over a 6-year period.